klammertext/doc/klammertext_for_llm.md

# Klammertext — reference for an LLM assistant

For a language model helping someone author Klammertext documents. Dense and
example-led on purpose: it is not a tutorial, and it motivates nothing. A person
wanting to learn Klammertext should read the other documents in `doc/`.

**Read §1 and §2 before writing any Klammertext.** §2 exists because a model that
has not seen this language will pattern-match it to LaTeX, Markdown, or Lisp and
produce confidently wrong syntax.

The klammers named here are the **Standard Klammer Set** (SKS), which is what
loads by default. A klammer set is user-extensible, so the authority for what
exists in any particular setup is `kdesc`, not this file — see §1. Where this
file and `kdesc` disagree, `kdesc` is right and this file is stale.

Vocabulary: text is **katomized** into **katoms** (the indivisible input units)
by **katom rewrite rules**; a **klammer** is the function-like operator; a
**target** is an output format; a **klammerset** is a named group of klammer
definitions. The three user modes are **author** (`@`), **designer** (`@@`),
**programmer** (`@@@`).

---

## 1. Do not guess — the machine will tell you

Klammertext is introspectable. `kdesc` **prints the live state of the machine's
data structures in digested form**. Query it instead of inferring from examples.

| ask | command |
|---|---|
| every klammer, with parameters and description | `kdesc -k` |
| klammers whose name or description mentions X | `kdesc -k X` |
| the output targets | `kdesc -t` |
| argument types and what each accepts | `kdesc --argtypes` |
| shared option groups and who uses them | `kdesc --optionsets` |
| which targets each klammer can render to | `kdesc --coverage` |
| what a user's own file defines (against the SKS) | `kdesc -i FILE -k` |
| the klammersets available, with provenance | `kdesc --klammersets` |
| how to write accented / non-English characters | `kdesc -c` |
| how to write any Unicode character, with examples | `kdesc -u` |
| installed typefaces; install or preview fonts | `kdesc --typeface`, `--typeface help` |
| the usage of any command | run it with no arguments (exit 0) |

`kdesc -k <name>` before using an unfamiliar klammer costs one command and
replaces a guess. The parameter list it prints is authoritative: a parameter
shows as `name.type default`, an option as `:name.type default`.

**Check a document without rendering it:**

```
kdiag --process --check doc.kt
```

reports every klammer application whose name, argument count, option names,
target coverage, or **literal argument value** is wrong (a value that fails
its argument type, such as `:width .5h`) — including inside `@cond` branches
this render will not take and inside klammer bodies never applied. A value
holding a nested klammer or a `*variable*` is computed at run time and is not
judged. It applies nothing. Use it before claiming a document is correct.

**Inspect how text is parsed:** `kdiag --type '<text>'` shows the katoms and
their types; `kdiag --args '<text>'` shows how text splits into arguments;
`kdiag --rewrite '<text>'` names the rewrite rule that fired. This settles
arguments about what a piece of syntax means. `kdiag` deliberately loads no
klammerset; give it `@read sks/sks.k @` in the input if it needs one.

---

## 2. What you will get wrong if you assume

| assumption | reality |
|---|---|
| It is a macro language like TeX | No catcodes. Katom structure is fixed when a file is read and cannot be changed by anything later. This is why static checking works. |
| `\command{arg}` | `@name arg @` — an `@` opens, and a **closing delimiter is required**. |
| Arguments are `{a}{b}` | Positional arguments are separated by `\|` — `@sup 2 \| 3 @`. |
| Options are `[key=value]` | `:name value`, anywhere in the argument list — `@link URL :text Click @`. |
| `%` starts a comment | `#` removes the rest of the line. `##` removes the rest of the file. `#[ … ]#` removes a block (nestable). |
| `*x*` is emphasis (Markdown) | `@i x @` is emphasis. `*name*` is **variable substitution** inside a klammer body; in prose write `^*` for a literal asterisk. |
| `\\` escapes | `^` quotes: `^@ ^\| ^# ^^ ^: ^*` and **`^` before any ASCII punctuation** gives that character literally. |
| `&`, `%`, `_`, `<`, `\` must be escaped for LaTeX/HTML | **Never.** The machine escapes the target's characters. An author quotes only Klammertext's own specials. Inside `@c`/`@code` nothing needs quoting. |
| `--` is two hyphens | Under every target `--` is an en dash, `---` an em dash, `` `` `` / `''` curly double quotes, `` ` ``/`'` curly single quotes, `~` a non-breaking space (the LaTeX conventions). A literal `--flag` is `^-^-flag`; a literal tilde `^~`. Verbatim text (`@c`, `@code`, `^'…'^`) is exempt. |
| Whitespace is insignificant | It is content, and it is preserved. Blank lines separate paragraphs. |
| Text is nested in braces | Text lives between the opening and closing delimiter with no wrapper. |
| The document body is the first argument | For `@document` the body goes in the **`:text` option** (or `:files`). A positional body is an error. |
| `x@i` is "x, then italic" | A letter may not touch an opening `@`: `x@i` could be the close of a klammer named `x`. Write `x @i`. Brackets and sentence punctuation may abut: `(@i-x)`, `@i x @.` |
| `:files ch1` names a file `ch1` | A bare word means **`kt/ch1.kt`** beside the root file. A name with a directory or extension is a pathname. |
| `@font` sets the font | Retired. `@typeface name \| text @` is the temporary change; `@document :serif_typeface` etc. set the roles. |

---

## 3. Core syntax

Three prefix tiers, distinguished by how many `@`:

| written | tier | meaning |
|---|---|---|
| `@name` | application | use a klammer |
| `@@name` | definition | define a klammer |
| `@@@name` | system | modify the machine (targets, argument types, state, klammersets) |

**Closing a klammer.** The close is `@` for the application tier, `@@` for
definitions, `@@@` for system commands. A close may be *named* by putting the
klammer's name immediately before it: `@i text i@`.

> **When to name the close.** Use a bare `@` by default. Use the named form
> `name@` when the body **contains other klammer calls**: if delimiters are
> unbalanced, a named close lets the machine say which klammer was left open.
> Do not name closes on short, klammer-free bodies — it is noise.

```
@i just text @                       ← bare close
@s1 A @c fragment c@ heading s1@     ← name it: the body contains a klammer call
```

**Arguments.**

```
@name positional1 | positional2 :option value :flag @
```

- `|` separates positional arguments.
- `:name value` is an optional argument; it may appear anywhere in the list.
  The value runs to the next `|` or `:option`.
- `:name` written alone takes the argument type's "alone" value — for a boolean
  that is `true`, so `:number` means `:number true`; `@table :hline` means
  `:hline all`.
- An optional argument that is not written takes its default (kdesc shows it).

**Abbreviated form.** `@name-arg1-arg2` is `@name arg1 | arg2 @`, valid only
while every argument is letters and digits: `@i-italic`, `@sup-2-3`, `@date@`.

**Literal klammers** take their content uninterpreted. It is not examined for
`@`, `|`, `#`, `^` or `*`, so the machine cannot find the end by counting and
**the named close is required**:

```
@code
  int x = a[0];   // # and @ are safe in here
code@

@c a | b c@      ← inline: same rule, and the close must be "c@"
```

`@c` and `@code` are the in-line and block forms of the same thing. Code that
lives in a **file** is `@source_listing`, never `@code` (which has no filename
argument):

```
@source_listing src/derivations.cpp @                       ← the whole file
@source_listing src/derivations.cpp :marker fromRdd55 @     ← one region of it
```

`:marker P` lists what lies between two lines that are exactly `//P` in column
one. A marker missing or not appearing exactly twice is an **error**, never a
fallback. `kdesc -k <name>` shows a literal parameter as `text.literal`.

**Whitespace and removal (`#`).** `#` rest of line, `##` rest of file, `#[ … ]#`
block; `#-` removes surrounding whitespace, `#+N` inserts N spaces, `#/N` inserts
N newlines (default 1).

**Characters (`^`).** One mechanism, four readings, in this order:

| form | gives | example |
|---|---|---|
| `^P` (P any ASCII punctuation) | that character literally | `^-^-flag`, `^~`, `^^`, `^@` |
| `^'…'^` | a **literal span**: raw target markup passed through untouched | `^'$\cdot$'^` |
| `^UUUU^` (4–6 hex digits) | the code point | `^0418^` И, `^263A^` ☺, `^13000^` 𓀀 |
| `^UUUU UUUU …^` | a run of code points, one caret pair | `^9053 53EF 9053^` 道可道 |
| `^` + base letter + mark | a diacritic | `^e'` é, `^u"` ü, `^n~` ñ, `^cc` ç, `^oh` ô |
| `^xx^` mnemonic | an extended-Latin letter | `^s^` ß, `^ae^` æ, `^o^` ø |

`kdesc -c` prints the diacritic, extended-Latin and pinyin tables; `kdesc -u`
the code-point notation with examples. The one `^` exception: `^'` opens a
literal span, so a literal apostrophe is `^0027^`. A caret form that names
nothing is an error, not silence.

---

## 4. A complete document

```
@document
:title Normalizing to OpenEXR Standard Attributes
:subtitle Predictability and provenance
:author Joseph Goldstone
:date @date@
:structure article
:point_size 12
:text

@s1 Principles s1@

Ordinary paragraph text. A blank line starts a new paragraph.
Use @i emphasis @ and @b bold @ inline, and @c code_fragment c@ for code.
A footnote @footnote Its text. @ is written inline.

@link https://openexr.com/ :text the OpenEXR site @

@ul
  first item
| second item
| third item
ul@

# A comment: removed, and never reaches the output.

@image figure_name :width .95w :caption A caption @

@table :caption Sizes :column_width fit fill
  | Name | Description
  || alpha | the first
  || beta | the second
table@

@
```

A long document names its chapters instead of holding them:

```
@document :title The Book :structure book :files preface one two @
```

which reads `kt/preface.kt`, `kt/one.kt`, `kt/two.kt` beside the root file.

**Render it:**

```
ktext doc.kt -t pdf          # also: -t html, -t tex
ktext doc.kt -t html         # writes a DIRECTORY doc/ containing index.html (+css, fonts, js)
ktext doc.kt -t txt -d       # -d displays on stdout instead of writing -- but this
                             #   example errors under txt/ansi: @image has no txt
                             #   definition (§5), and coverage is never silently degraded
ktext -s '@i-x' -t html -d   # -s takes a string; no file needed
ktext doc.kt -s '@@version : 3.2.1 @@' -t pdf   # -s is processed BEFORE the files:
                                                #   define a klammer the document uses
```

- Output goes **next to the input file** unless `-o` names a directory and/or
  basename. String-only input writes to the current directory.
- `-s`, `-t`, `-o` take exactly one argument (quote spaces). `--klammersets`
  takes a list; end it with `--` if filenames follow.
- Filenames may contain spaces: quote them on the command line; in a list
  (`:files`, several input files) separate names with a standalone ` / `.
- `@document :structure` is `plain` (default; no TOC), `article` (in-page
  TOC), `book` (cover, navigation panel in html; chapters, recto/verso in
  pdf). Headings `@s1`… are `\chapter` in a book and `\section` otherwise.
- Role typefaces: `:serif_typeface`, `:sans_typeface`, `:mono_typeface`
  (family name or store directory name, e.g. `EB Garamond` or `eb-garamond`);
  `:text_scale` scales all text; `:point_size`, `:leading`, `:paper_size`,
  `:landscape`, `:two_column`. `kdesc -k document` lists all forty.
- **Outside a `@document`** nothing makes paragraphs: a fragment rendered on
  its own writes `@par text @` explicitly.

---

## 5. Klammers most used when authoring

Confirm parameters with `kdesc -k <name>` — this is names and intent only.
Not every klammer exists for every target (`kdesc --coverage`); txt and ansi
are the limited ones.

| | |
|---|---|
| inline | `@i` italic, `@b` bold, `@t` typewriter, `@u` underline, `@s` sans, `@r` roman, `@ri` roman italic, `@c` inline code (literal; close `c@`), `@sup base \| script @`, `@sub`, `@ts scale \| text @` resize, `@color rgb :text`, `@typeface name \| text :scale @`, `@cjk` (needs an installed CJK typeface) |
| structure | `@s1`…`@s7` numbered headings, `@h1`…`@h7` unnumbered, `@part`, `@preface`, `@par`, `@newpage`, `@vspace lines`, `@vfill`, `@nl` line break |
| blocks | `@code` (inline listing), `@source_listing file :marker P`, `@quote text \| attribution @`, `@note`, `@indent :left :right`, `@center`, `@right`, `@block to \| content @` (absolute placement), `@columns items :n @`, `@multicolumn text :n :gap @`, `@lines` |
| lists | `@ul :bullet`, `@ol :initial`, `@define :style` term/definition, `@qa question \| answer @` — items separated by `\|` |
| tables | `@table` — cells by `\|`, rows by `\|\|` (§6); `@rowcolor` |
| figures & references | `@image basename :width :caption`, `@image_grid`, `@fig id`, `@tbl id`, `@reference spec \| name @`, `@target id :text` |
| footnotes & links | `@footnote text @`, `@link target :text :footnote`, `@email name \| domain @` |
| dates | `@date`, `@datetime` (`:days N`, `:lang de`, `:number`), `@year`, `@timestamp` |
| symbols | `@copyright`, `@registered`, `@trademark`, `@euro amount`, `@pi`, `@rightarrow`, `@dot`, `@sp` (space) |

Bar depth is the dimension: one `|` separates items, two `||` separates rows.
Argument order is free for options, fixed for positionals.

**Coverage today** (`kdesc --coverage`; 89 klammers): html, tex and pdf cover
nearly all. **txt and ansi cover 40**, among them `@b @i @t @u @s @r @ri @ts
@typeface`, `@s1`–`@s7`, `@par @newpage @vspace @vfill @nl`, `@indent @right
@lines @qa`, `@ul @ol`, `@table @tbl @reference @define @left_right`,
`@footnote @link`, `@date @datetime`, `@c`. Not for txt: `@code
@source_listing @image @image_grid @quote @note @center @block @columns
@multicolumn @sup @sub @color @h1`–`@h7`.
`@u` has no html definition. A klammer applied under a target that lacks it is
an **error**, never silently dropped.

---

## 6. Tables

```
@table :caption Quarterly :column_width fit fit fill :cell_hpos l r r :calc 3(1-2) = + 1-2(1-2)
  | Item | Q1 | Q2
  || Widgets | 10.5 | 12
  || Gadgets | 3 | 4.25
  || Total | |
table@
```

Cell indices are **zero-origin and count the header row**: `3(1-2)` is the
fourth row, second and third columns; `1-2(1-2)` the two body rows above it;
`-1` is the last row or column. A ranged target repeats the calculation across
the range (here: one sum per column).

- First row is the header (`:header false` otherwise); header style
  `:header_style i` by default; `:style r i b` per column.
- `:column_width` per column: `fit` (widest entry), `fill` (the remaining
  width, capped at the widest entry), a fraction of the text width (`.2`), or
  `*` (the remainder). `fill` may not combine with a fraction or `*`.
- `:cell_hpos l c r` per column; `:justify <cells> <pos>; …` per cell.
- Lines: default under the header and at the bottom; `:hline`/`:vline`
  replace them (`all`, `none`, or indexed ranges); `:grid` for all lines.
- `:colspan`/`:rowspan` with the indexed-range syntax; `:allow_break true`
  makes a page-breaking table (pdf).
- `:calc` — `;`-separated `<row>(<col>) = <op> <operands>`, prefix `+ - * /`
  folding left over the operands, which are cell ranges or numbers;
  **display-precision** (a printed total equals the sum of the printed lines);
  `notes/calc_notation.md` is the gallery. `:format <cells> module.function`
  formats cells with user Python. `:decimal comma` for comma decimals.
- Placement: `:hpos left|center|right|none`, `:offset 2em` (inset from that
  margin); a caption goes **above** a table (`:caption_side top` default),
  below a figure. `:number false` for an unnumbered caption.

---

## 7. Targets

| target | output | notes |
|---|---|---|
| `html` | a directory `<name>/` with `index.html`, `css/`, `fonts/`, `js/` | self-contained, fonts localized; `book` structure adds navigation, search |
| `tex` | `<name>.tex` | XeLaTeX source; fonts via fontspec from the font store |
| `pdf` | `<name>.pdf` | `tex` plus a xelatex run (TeX Live required) |
| `txt` | `<name>.txt` | plain text filled to `Target_txt_width` (72), blocks indented by `Target_txt_indent` (3); tables ruled and padded; captions numbered; **40 of 89 klammers** (§5) |
| `ansi` | txt + SGR escape sequences | `@b`/`@i`/`@u` and table header styles shown by a terminal; **identical to txt once the escape sequences are stripped**; pick it with `-t ansi -d`; a terminal needs a font with an italic face (macOS Terminal: Menlo, not Monaco) |

`k`, `o`, `*` also appear in `kdesc -t`: they are declaration pseudo-targets
(interface, option set, all targets), not outputs.

State variables an author may set (`@@@state Name :value V @@@` in the
document, or `-s`): `Language` (`en`/`de`, for dates), `Image_quality` (JPEG
quality of cached photographs, 85), `Target_txt_width`, `Target_txt_indent`,
`Image_default_width`, `Image_search_path`.

Typefaces: the **font store** is closed-world (no network). The distribution
ships eb-garamond, crimson-pro, open-sans, source-sans-3, inconsolata,
source-code-pro, noto-sans-egyptian-hieroglyphs, noto-sans-cuneiform (see
`kdesc --typeface`); more are installed with `kdesc --typeface install <dir>`
into `KLAMMERTEXT_FONTS`. An unknown typeface is an error listing the available
ones. CJK is deliberately not shipped.

---

## 8. Defining klammers (only if asked)

```
@@name.k arg1 | arg2 :opt.type default : Description of what it does @@
@@name.html :: <span>*arg1*</span> @@
@@name.tex  :: \textbf{*arg1*} @@
@@name.txt  :: *arg1* @@
```

- `.k` declares the interface and documents it; per-target definitions inherit
  the parameter list with `::`. Every target's list must agree.
- `*arg*` substitutes an argument into the body; `*Name*` also reads a state or
  environment variable.
- Several targets may share a body: `@@name.html,tex :: … @@`. A definition
  with **no suffix** applies to every target (the writer's macro form; its body
  is escaped for the target, so `@@corp : Smith & Jones @@` is safe). `.*`
  written out is a *claim* of target independence.
- Separators: `:` create, `::` create inheriting parameters, `:::` override an
  existing definition, `::::` define a default a later `:` may replace.
- Argument types: `name.type` — `string` (default), `int`, `float`, `bool`,
  `list`, `width`/`height` (a bare number = characters / lines in every
  target; units `em pt px`, `w pw` for widths, `h ph` for heights; the axes
  are checked), `literal` (raw content, named close required), `rest`
  (everything left, bars included; `rest(2)` = list of lists), and any
  `@@@argtype` the klammerset declares (`kdesc --argtypes`). An argtype may
  carry `:default` and `:alone`; a klammer may override the default, never the
  alone value.
- **Option sets** (`.o`): a named group of optional parameters used by several
  klammers — `@@name.k arg @caption_args :caption_side top @ : … @@` splices
  the SKS's caption options with one default overridden. Usable only in a `.k`
  parameter list. A klammer *application* inside a parameter list is an error.
- **`@eval`** is the primitive behind every non-trivial klammer:
  `@eval python_expr @` (module.function auto-imports; `K` holds the
  arguments), `@eval :cpp lib.function @`, `@eval :shell cmd @`,
  `@eval :haskell src @`; `:cwd DIR` runs it there (`:cwd *K_input_dir*`).
  A Python module is found next to the file that names it. **The result is
  re-read as Klammertext**: a result holding klammers is *generator* output and
  its text is escaped for the target; a result with none is *renderer* output
  and left alone. A literal `@` in a result must be emitted as `^@`.
- A klammer whose tex body is target markup with a backslash must not be
  passed through a generator raw — the SKS carries such things as markers
  (`@nl`), resolved in an `:after_apply` phase.
- **Klammersets**: `@@@klammerset sym | description :requires sks :files a.k b.k @@@`
  in `sym/sym.k`; loaded with `ktext --klammersets sym doc.kt` (symbols only,
  resolved in the document's directory, then `KLAMMERTEXT_KLAMMERSETS`, then
  the distribution; several combine in order, later definitions deciding
  collisions via the separators above). `kdesc -i file.k -k` shows what a file
  defines against the SKS. `--klammersets ref` adds the reflection klammers
  (`@diacritics_examples@`, `@unicode_examples@`, …) that generate the
  reference tables `kdesc -c`/`-u` print.

---

## 9. Behaviour worth knowing before you debug something

- **`@cond` is strict about truth.** True: `true`, `True`, `1`. False: `false`,
  `False`, `0`, empty. **Anything else is an error**, not "probably false".
- **`@cond` is resolved at application time and evaluates only the branch it
  selects.** A `@read`/`@eval` in the other branch does not run. A top-level
  `@cond *Flag* | … @` sees the variable's value.
- **A state variable is visible from the moment its declaration is read** —
  in every klammer body applied afterwards and in the top-level text of later
  input units, but not in the top-level text of the same unit that declares it.
  Declare early (`-s`, a first file, a klammerset).
- **A definition inside a `@cond` branch does not register** — in either
  branch. Define outside and select between *applications*.
- **`@eval :shell` and `:haskell`:** stdout becomes document text; stderr does
  not (shown under `-v 1`); a nonzero exit is an error. Append `|| true` if a
  nonzero exit is expected.
- **Arguments arrive as written**, nested klammers already rendered; a macro
  escapes only its own body text. Never escape an output format's characters
  yourself, anywhere.
- **Typographic transforms are per katom and skip verbatim text**: a `--` split
  by a klammer is two hyphens; inside `@c`/`@code` nothing is transformed.
- **Recursion** is guarded: a klammer reaching itself 200 deep is a named
  `Recursion_error`; a document needing more than 100 top-level passes is an
  error.
- **`@eval` results are trimmed**; a klammer that must emit leading space or
  pure vertical space uses the txt/tex markers the SKS provides
  (`phases.txt_nbsp_marker()`, `@vspace`).
- The html **page cache** (`/dev/shm/_klammertext_cache/` on Linux) can serve
  a stale page after a change to a klammer's html; clear it when output looks
  old (`@document :cache false` disables it).

---

## 10. Diagnostics and what the commands print

- Three cases only: **logging** (stderr, `-v` > 0), **an error** (stderr, then
  exit ≠ 0), **the requested output** (stdout). So `ktext doc.kt -t txt -d | …`
  is safe; nothing else lands in the document.
- **`-v 1`** reports every decision the user could not read off their input:
  which klammerset loaded and from where, which file a typeface or `:files`
  name resolved to, how the output path was built, an override of another
  set's definition. `-v 2`+ is an implementation trace.
- An error stops the run and names a file, line and character; messages are
  justified to 80 columns. There is **no warn-and-continue** except two
  aggregated heuristics: unknown target coverage, and a table wider than the
  page.
- *"Word not parsed: …"* means a piece of text matched no katom type — usually
  a letter touching a delimiter (§2) or a punctuation run needing `^`.
- Colour on stderr only when it is a terminal; `NO_COLOR` disables it. kdesc's
  `-c`/`-u` render through `ansi` on a terminal and `txt` in a pipe.

**When something is wrong:** `kdiag --process --check doc.kt` first (name,
arity, option, literal-value and coverage faults without rendering); then `kdesc -k <klammer>`
against what was written; then `kdiag --type '<fragment>'` if the question is
how something is parsed; then `ktext … -v 1` if the question is which file or
klammerset was used.

---

## 11. Klammertext from Python

```python
import klammertext                                   # kpy/ on PYTHONPATH (env/runtime.env)
M = klammertext.Machine(target="html", files=["doc.kt"])   # as ktext sets itself up
M.read("@@version : 3.2.1 @@")                       # what "ktext -s" does
M.read_files()                                       # the constructor's files, in order
html = M.apply()                                     # the rendered text
```

`Machine(target='*', klammersets=None, files=None, output=None, display=False,
verbose=0)`; `read(text)`, `read_file(name)`, `read_files()`,
`apply(target=None, final_processing=True, escape_characters=True)`. **One
Machine at a time** (a second raises `RuntimeError`); `apply()` reduces in
place, so a second target needs a second Machine. Errors are `klammertext.Error`
subclasses under the C++ names (`Parsing_error`, `Argument_error`,
`Definition_error`, `Environment_error`, …) with `kind`, `description`,
`filename`, `line`, `column`; `str(e)` is ktext's report; an `@eval`'s Python
exception is chained as `__cause__`.

---

## 12. Adjacent tools

- **Markdown → Klammertext:** `sks/tns/md_to_sks.py` converts a `.md` file;
  what it cannot convert exactly is left in the output as `#[MD … ]#` markers,
  so the draft carries its own worklist (spec: `doc/markdown_to_klammertext.md`).
  `mdpdf file.md` renders Markdown straight to PDF through a headless Chromium,
  bypassing Klammertext.
- **Editors:** `doc/edit/` holds Emacs, Sublime Text, Vim and VS Code support
  (highlighting, delimiter matching, reindent, table alignment, a language
  server); `doc/edit/README.md`.
- **Containers:** `akopra/klammertext:latest` (and `:haskell`) hold the three
  commands, the SKS, TeX Live and the default fonts; `doc/linux_container_install.md`,
  `doc/macos_container_install.md`.
- **Environment:** `KLAMMERTEXT_HOME` (the tree), `KLAMMERTEXT_FONTS`,
  `KLAMMERTEXT_KLAMMERSETS` (colon-separated search paths); `env/runtime.env`
  sets them when sourced.